🫀 HK-MLE High-Yield MCQ Bank: Arrhythmias

50 Clinical Vignette MCQs | Based on Davidson's, Harrison's 22E, Washington Manual, Tintinalli's & 2024 ESC AF Guidelines

━━━ SECTION A: ATRIAL FIBRILLATION (Questions 1–13) ━━━

• A) Aspirin 100 mg daily
• B) Aspirin 100 mg plus clopidogrel 75 mg daily
• C) Warfarin targeting INR 2–3
• D) Apixaban 5 mg twice daily
• E) No anticoagulation required as he is rate-controlled

• A) Aspirin monotherapy is inadequate for stroke prevention in AF with CHA₂DS₂-VASc ≥2 and is no longer recommended by ESC 2024 guidelines.
• B) Dual antiplatelet therapy is inferior to anticoagulation and is reserved only for patients who absolutely cannot tolerate any anticoagulant.
• C) Warfarin is acceptable but is second-line to DOACs for non-valvular AF; reserved for valvular AF (mitral stenosis) or mechanical heart valves where DOACs are not studied or contraindicated.
• E) Rate control addresses symptoms but does not reduce thromboembolic risk; anticoagulation must be addressed independently of rate/rhythm status.

• A) No anticoagulation needed if DOAC given 4 hours before
• B) 2 weeks of therapeutic anticoagulation pre-cardioversion
• C) 3 weeks of therapeutic anticoagulation pre-cardioversion, followed by 4 weeks post
• D) Immediate cardioversion with IV heparin bolus only
• E) Cardioversion is contraindicated without surgical left atrial appendage occlusion

• A) A short DOAC course of 4 hours is insufficient; alternatively, TOE-guided cardioversion can exclude LAA thrombus allowing earlier procedure, but requires full post-cardioversion anticoagulation regardless.
• B) Two weeks is insufficient; 3 weeks is the minimum recommended per ESC 2024 and ACC/AHA guidelines.
• D) IV heparin alone covers the peri-procedural period but does not address pre-existing LAA thrombus that may have formed during AF.
• E) LAA occlusion (e.g., Watchman device) is an alternative to long-term anticoagulation, not a prerequisite for cardioversion.

• A) Verapamil 80 mg three times daily
• B) Diltiazem 60 mg three times daily
• C) Bisoprolol 2.5 mg daily
• D) Flecainide 100 mg twice daily
• E) Sotalol 80 mg twice daily

• A) Verapamil is a non-dihydropyridine CCB with significant negative inotropic properties; it is contraindicated in HFrEF as it can precipitate acute decompensation.
• B) Diltiazem shares the same negative inotropic risk as verapamil and is contraindicated in HFrEF.
• D) Flecainide is a Class Ic antiarrhythmic used for rhythm control (not rate control) and is contraindicated in structural heart disease or HFrEF due to proarrhythmic risk (CAST trial).
• E) Sotalol has Class II and III properties and is generally avoided in HFrEF due to risk of QT prolongation and proarrhythmia; it is not a first-line rate control agent.

• A) Apixaban 2.5 mg twice daily (full dose reduction criteria met)
• B) Rivaroxaban 15 mg daily (renal dose)
• C) Dabigatran 110 mg twice daily
• D) Dabigatran 75 mg twice daily
• E) No change; continue warfarin as DOACs are contraindicated in CKD

• A) Apixaban dose reduction to 2.5 mg twice daily requires meeting ≥2 of 3 criteria: age ≥80, weight ≤60 kg, creatinine ≥133 µmol/L; this patient meets only one criterion (depending on weight/age), so 5 mg BD would be appropriate, not 2.5 mg BD.
• C) Dabigatran 110 mg twice daily is a standard dose option (for age ≥80 or high bleeding risk); at eGFR 30–50, 110 mg BD is acceptable, but caution is needed below eGFR 30.
• D) Dabigatran 75 mg twice daily is a US-specific dose for eGFR 15–30 mL/min; it is not widely endorsed in European/HK guidelines.
• E) DOACs are generally preferred over warfarin in CKD stage 3; warfarin is still an option but is not automatically mandated; DOACs are contraindicated only at eGFR <15 mL/min (end-stage CKD).

• A) IV metoprolol 5 mg
• B) IV verapamil 5 mg
• C) IV amiodarone 300 mg over 1 hour
• D) Synchronised DC cardioversion 200 J (biphasic)
• E) IV adenosine 6 mg rapid bolus

• A) IV beta-blockers are contraindicated in haemodynamically unstable AF with acute pulmonary oedema; negative inotropy can worsen cardiogenic shock.
• B) IV verapamil is similarly contraindicated in haemodynamic instability; it can cause fatal cardiovascular collapse in this context.
• C) IV amiodarone can be used for rate/rhythm control in stable AF with HF; it is too slow for immediate haemodynamic rescue and is second-line to cardioversion.
• E) Adenosine terminates re-entrant SVTs but has no role in AF; it will not convert AF and may cause transient worsening of hypotension.

• A) Amiodarone 200 mg daily
• B) Flecainide 100 mg twice daily
• C) Sotalol 80 mg twice daily
• D) Digoxin 125 mcg daily
• E) Dronedarone 400 mg twice daily

• A) Amiodarone is highly effective but is reserved for last-line or structural heart disease cases due to extensive toxicity profile (thyroid, pulmonary, hepatic, corneal deposits, photosensitivity) with long-term use.
• C) Sotalol is an option but requires QTc monitoring and has beta-blocking side effects; it is less preferred than flecainide in young patients with no structural disease.
• D) Digoxin provides rate control, not rhythm control; it does not maintain sinus rhythm.
• E) Dronedarone is a Class III agent (amiodarone analogue without iodine) and can be used for rhythm control in non-permanent AF without severe HF; however, it is contraindicated in permanent AF and HFrEF, and flecainide is preferred in structurally normal hearts.

• A) HAS-BLED ≥3 is a contraindication to anticoagulation; withhold all anticoagulants
• B) HAS-BLED score should be used to identify and correct modifiable bleeding risk factors, not to withhold anticoagulation
• C) Antiplatelet monotherapy is preferred when HAS-BLED is ≥2
• D) Aspirin plus DOAC combination reduces net clinical risk in AF with HAS-BLED 2
• E) Rivaroxaban is contraindicated when HAS-BLED ≥2

• A) No absolute HAS-BLED threshold contraindicates anticoagulation; even HAS-BLED ≥3 warrants correction of reversible factors and continued anticoagulation if thromboembolic risk is high.
• C) Antiplatelet therapy is inferior to anticoagulation for stroke prevention and has similar or higher bleeding risk; it is not a safe alternative.
• D) Combining antiplatelet agents with DOACs significantly increases major bleeding without additional stroke prevention benefit in most AF patients.
• E) No DOAC is specifically contraindicated based on HAS-BLED score alone.

• A) Warfarin is absolutely contraindicated in CKD stage 4
• B) All DOACs are equally safe in eGFR 15–29 mL/min
• C) Apixaban has the least renal elimination and may be preferred in advanced CKD
• D) Dabigatran is the preferred DOAC at eGFR <30 mL/min
• E) Haemodialysis patients should receive apixaban 5 mg twice daily without dose adjustment

• A) Warfarin is not contraindicated in CKD stage 4; it is renally cleared minimally and remains an option, though DOACs are increasingly used.
• B) DOACs differ substantially in renal clearance; dabigatran (80% renal) is most affected by CKD and should be avoided at eGFR <30 mL/min.
• D) Dabigatran is contraindicated or strongly cautioned at eGFR <30 mL/min due to accumulation risk; it is the least preferred DOAC in advanced CKD.
• E) Haemodialysis patients have limited DOAC data; warfarin or careful apixaban dosing (2.5 mg BD) may be considered, but 5 mg BD without adjustment is not recommended.

• A) Triple therapy (DOAC + aspirin + clopidogrel) indefinitely
• B) Dual therapy (DOAC + P2Y12 inhibitor, e.g., clopidogrel) for 12 months, then DOAC monotherapy
• C) DOAC monotherapy only
• D) Warfarin + aspirin + ticagrelor for 6 months
• D) Aspirin 100 mg + clopidogrel 75 mg indefinitely; stop DOAC

• A) Prolonged triple therapy significantly increases major bleeding without substantial reduction in ischaemic events (AUGUSTUS, ENTRUST-AF PCI trials).
• C) DOAC monotherapy provides stroke prevention but inadequate coronary stent protection in the first months after PCI.
• D) Warfarin-based triple therapy has higher bleeding rates than DOAC-based regimens and is no longer preferred; ticagrelor increases bleeding risk in triple therapy.
• E) Stopping anticoagulation leaves the patient unprotected against AF-related stroke.

• A) Administering IV adenosine
• B) Administering IV amiodarone
• C) Administering IV procainamide
• D) Synchronised DC cardioversion
• E) Administering IV magnesium

• B) Amiodarone is also relatively contraindicated in pre-excited AF as it may enhance accessory pathway conduction (similar to adenosine); IV procainamide or DC cardioversion is preferred.
• C) IV procainamide (Class Ia) is the preferred agent in haemodynamically stable pre-excited AF; it slows accessory pathway conduction.
• D) DC cardioversion is appropriate if the patient becomes haemodynamically unstable and is a safe definitive option in pre-excited AF.
• E) IV magnesium has no role in pre-excited AF and is not the most dangerous option here, but it is also not indicated.

• A) Increase warfarin dose and recheck INR monthly
• B) Add aspirin to improve stroke prevention while re-titrating warfarin
• C) Switch to a DOAC (e.g., apixaban or rivaroxaban)
• D) Refer for Watchman left atrial appendage occlusion device immediately
• E) Stop anticoagulation and reassess in 3 months

• A) Simply increasing the dose without addressing the root cause (compliance, dietary factors, drug interactions) is unlikely to achieve sustained TTR improvement.
• B) Adding aspirin to warfarin increases bleeding without improving stroke prevention.
• D) LAA occlusion is a reasonable alternative to long-term anticoagulation in patients with high bleeding risk or anticoagulation failure, but switching to a DOAC is the immediate first step.
• E) Stopping anticoagulation in a CHA₂DS₂-VASc 5 patient would dramatically increase stroke risk and is not justified.

• A) Age 75 years or older (2 points)
• B) Female sex (1 point)
• C) Diabetes mellitus (1 point)
• D) Peripheral vascular disease (1 point)
• E) Obesity (BMI >30) (1 point)

• A) Age ≥75 correctly scores 2 points in CHA₂DS₂-VASc.
• B) Female sex scores 1 point but is a risk modifier; a score of 1 in females alone does not mandate anticoagulation.
• C) Diabetes mellitus scores 1 point correctly.
• D) Peripheral vascular disease (prior MI, aortic plaque, PAD) contributes 1 point under the "V" (vascular disease) component.

• A) Anticoagulation can be stopped immediately after successful cardioversion
• B) Anticoagulation should continue for 4 weeks post-cardioversion only
• C) Anticoagulation should continue long-term based on CHA₂DS₂-VASc score, independent of rhythm
• D) Anticoagulation can be stopped after 3 months if sinus rhythm is maintained
• E) Anticoagulation is only needed if AF recurs

• A) Stopping immediately post-cardioversion ignores post-cardioversion atrial stunning and ongoing arrhythmia recurrence risk.
• B) The 4-week post-cardioversion anticoagulation covers stunning but does not address the long-term stroke risk from future AF episodes.
• D) Three months is insufficient; guidelines do not recommend stopping based on rhythm maintenance alone.
• E) Silent (asymptomatic) AF is common and would be missed; waiting for symptomatic recurrence before anticoagulating is dangerous.

━━━ SECTION B: SVT / AVNRT / WPW (Questions 14–24) ━━━

• A) IV verapamil 5 mg
• B) IV metoprolol 5 mg
• C) IV adenosine 6 mg rapid bolus via antecubital vein, followed by 12 mg if needed
• D) Synchronised DC cardioversion 50 J
• E) IV flecainide 2 mg/kg

• A) IV verapamil is a valid alternative but is second-line to adenosine; it must be avoided if beta-blockers have recently been given (risk of severe bradycardia/asystole).
• B) IV beta-blockers can terminate SVT but are slower in onset and less effective than adenosine for acute termination.
• D) DC cardioversion is reserved for haemodynamically unstable SVT; this patient is stable with BP 110/70 mmHg.
• E) IV flecainide is used for rhythm conversion in AF/flutter or prevention of SVT, not acute narrow-complex SVT management.

• A) The risk of sudden cardiac death (SCD) is very high (>50% annual risk)
• B) The accessory pathway in WPW syndrome always conducts both anterograde and retrograde
• C) Catheter ablation of the accessory pathway achieves cure in >90% of cases
• D) Beta-blockers are absolutely contraindicated in all WPW patients
• E) The presence of a delta wave confirms symptomatic WPW requiring mandatory ablation

• A) The overall annual SCD risk in WPW is approximately 0.1–0.3%; it is low in most patients, though risk is higher in those with short effective refractory period of the accessory pathway.
• B) Some accessory pathways are concealed (retrograde conduction only) and do not produce delta waves on resting ECG; anterograde conduction is necessary for pre-excitation (delta wave).
• D) Beta-blockers can be used for AVRT prevention in WPW without pre-excited AF; they are dangerous in pre-excited AF (block AV node, accelerate accessory pathway) but are not universally contraindicated.
• E) Asymptomatic pre-excitation (incidental delta wave) does not automatically require ablation; risk stratification with EP study guides the decision.

• A) IV adenosine 12 mg
• B) IV digoxin 0.5 mg
• C) IV verapamil 10 mg
• D) Synchronised DC cardioversion 200 J biphasic
• E) IV propranolol 1 mg

• A) Adenosine in pre-excited AF is a classic HKMLE trap — it blocks the AV node, funnelling all conduction through the accessory pathway, potentially inducing VF.
• B) Digoxin shortens the refractory period of the accessory pathway and increases the risk of VF in pre-excited AF; it is absolutely contraindicated.
• C) Verapamil blocks the AV node and may enhance accessory pathway conduction; it is contraindicated in pre-excited AF and may cause haemodynamic collapse.
• E) IV propranolol similarly blocks AV nodal conduction and can unmask rapid accessory pathway conduction; contraindicated in pre-excited AF.

• A) Sinus tachycardia
• B) Atrial tachycardia
• C) AVNRT (typical, slow-fast)
• D) AVRT using a concealed accessory pathway
• E) Junctional tachycardia

• A) Sinus tachycardia has upright P waves preceding each QRS; P waves are not buried in or just after the QRS.
• B) Atrial tachycardia produces P waves before the QRS (long RP), often with a morphology different from sinus P waves.
• D) AVRT via a concealed pathway also produces a short RP tachycardia but typically has a longer RP interval than AVNRT (>70 ms); distinction requires EP study.
• E) Junctional tachycardia (junctional automatic tachycardia) is uncommon in adults; it tends to occur post-cardiac surgery in children.

• A) Positive delta wave in V1, negative in aVL
• B) Negative delta wave in V1, positive in I and aVL
• C) Positive delta wave in V1, positive in inferior leads (II, III, aVF)
• D) Negative delta wave in inferior leads, positive in V1
• E) Isoelectric delta wave in I, positive in III

• A) Positive delta in V1 with negative aVL suggests a right lateral or posteroseptal pathway.
• C) Positive delta in V1 with positive inferior leads suggests an antero-septal or right-sided pathway.
• D) Negative inferior delta waves suggest a posteroseptal or inferior accessory pathway.
• E) This pattern does not correspond to a standard WPW localisation schema for left lateral pathways.

• A) Standard Valsalva (strain for 15 seconds)
• B) Modified Valsalva: strain supine 15 seconds, then immediately lie supine with legs raised 45°
• C) Carotid sinus massage, right side, firm 5-second pressure
• D) Ice-cold water immersion of face (diving reflex)
• E) Breath-hold followed by immediate deep inspiration

• A) Standard Valsalva terminates only ~5–17% of SVT episodes; it is less effective than the modified technique.
• C) Carotid sinus massage is contraindicated in patients with carotid bruit or recent stroke; it is an alternative but has lower efficacy than the modified Valsalva.
• D) The diving reflex (cold water facial immersion) can increase vagal tone but is uncomfortable and impractical in A&E; not first-line.
• E) This is not a recognised vagal manoeuvre and has no evidence base.

• A) QRS duration 130 ms
• B) Bundle branch block morphology identical to prior sinus rhythm ECG
• C) AV dissociation on the rhythm strip
• D) Rate-related left bundle branch block pattern
• E) Termination with IV adenosine

• A) QRS duration >140 ms is suggestive of VT but not specific; SVT with aberrancy can also produce wide QRS.
• B) If the bundle branch block pattern during tachycardia is identical to that during sinus rhythm, SVT with pre-existing BBB is more likely.
• D) Rate-related (phase 3) BBB during SVT produces aberrant conduction mimicking VT; this favours SVT with aberrancy.
• E) Adenosine termination is more consistent with SVT (AVNRT or AVRT); however, some fascicular VTs are adenosine-sensitive, so this is not a definitive discriminator.

• A) IV adenosine is contraindicated in pregnancy
• B) DC cardioversion is contraindicated in pregnancy
• C) Adenosine is safe and remains first-line for acute SVT; foetal monitoring required
• D) Flecainide is the drug of choice for acute SVT in pregnancy
• E) Verapamil is preferred over adenosine in all trimesters

• A) Adenosine is not contraindicated in pregnancy; it is the preferred agent due to its safety profile and rapid elimination.
• B) DC cardioversion is safe in pregnancy when clinically indicated; foetal monitoring is required during the procedure.
• D) Flecainide is used for foetal arrhythmias (transplacental delivery) and maternal AF, not acute SVT management; it is Class C/D and avoided unless necessary.
• E) Verapamil is relatively contraindicated in the third trimester due to risk of neonatal hypotension and is not preferred over adenosine.

• A) AVNRT is the most common SVT in the elderly but rare in young adults
• B) AVNRT requires an accessory pathway for its re-entry circuit
• C) Typical (slow-fast) AVNRT accounts for approximately 90% of AVNRT cases
• D) Radiofrequency ablation of the slow pathway has a success rate of approximately 60%
• E) AVNRT always produces visible retrograde P waves preceding the QRS

• A) AVNRT is the most common SVT in middle-aged adults (especially women); it is not particularly uncommon in young adults.
• B) AVNRT uses the dual AV nodal pathway (slow and fast pathway) within or near the AV node; no accessory pathway is required (unlike AVRT in WPW).
• D) RF ablation of the slow AV nodal pathway has a success rate of >95%, not 60%.
• E) In typical AVNRT, retrograde P waves are buried within or at the terminal portion of the QRS (pseudo-R' in V1); they appear just after the QRS, not before it.

• A) Atorvastatin
• B) Metformin
• C) Metoprolol
• D) Omeprazole
• E) Amlodipine

• A) Atorvastatin has no clinically relevant effect on heart rate or AV conduction.
• B) Metformin has no cardiac conduction effects.
• D) Omeprazole has no clinically significant cardiac conduction interaction.
• E) Amlodipine is a dihydropyridine CCB with minimal AV nodal effects; it does not significantly potentiate bradycardia with verapamil.

• A) Permanent pacemaker implantation
• B) Prescribe flecainide prophylactically
• C) Restriction from competitive sport until EP study performed
• D) EP study to assess accessory pathway effective refractory period; consider ablation if high-risk
• E) Reassure and discharge; no further action needed

• A) A permanent pacemaker is inappropriate; it treats bradycardia, not tachyarrhythmias associated with WPW.
• B) Empirical antiarrhythmics without risk stratification are not indicated in asymptomatic WPW; drugs alone do not eliminate SCD risk from accessory pathway.
• C) Exercise restriction alone without diagnostic evaluation is not the complete answer; the ESC recommends EP-guided risk stratification.
• E) Simply reassuring an asymptomatic athlete without further evaluation is inappropriate given the potential for SCD during high-intensity sport.

━━━ SECTION C: VENTRICULAR TACHYCARDIA & TORSADES (Questions 25–37) ━━━

• A) IV adenosine 6 mg
• B) IV lidocaine 1 mg/kg
• C) IV amiodarone 300 mg over 20–60 minutes
• D) Synchronised DC cardioversion 200 J (biphasic)
• E) Unsynchronised defibrillation 360 J (monophasic)

• A) Adenosine is for SVT and is ineffective in VT; it may cause haemodynamic deterioration in an already unstable patient.
• B) IV lidocaine can terminate haemodynamically stable VT but is too slow for an unstable patient.
• C) IV amiodarone is appropriate for haemodynamically stable sustained VT and pulseless VT in shock-refractory cardiac arrest, but cardioversion is preferred for unstable VT.
• E) Unsynchronised (asynchronous) defibrillation is used for pulseless VF or pulseless VT; in VT with a pulse, unsynchronised shock can precipitate VF by falling on the T wave.

• A) QRS duration 140 ms
• B) Capture beats and fusion beats visible on rhythm strip
• C) Right bundle branch block morphology in V1
• D) Concordance of QRS in all chest leads, all negative (negative concordance)
• E) Both B and D

• A) QRS duration of 140 ms alone is not specific; LBBB during SVT can produce similar widening.
• B) Capture/fusion beats alone are independently diagnostic of VT.
• C) RBBB morphology in V1 is not specific; SVT with aberrant RBBB conduction produces similar patterns.
• D) Negative concordance alone is a highly specific VT criterion (Brugada algorithm).

• A) IV amiodarone 300 mg
• B) Synchronised DC cardioversion 200 J then IV sotalol
• C) IV magnesium sulphate 2 g over 10–15 minutes
• D) IV lidocaine 1 mg/kg
• E) IV metoprolol 5 mg

• A) Amiodarone further prolongs the QT interval and is absolutely contraindicated in TdP; it will worsen the arrhythmia.
• B) Cardioversion can be used if TdP is sustained and causes haemodynamic compromise, but sotalol (Class III, prolongs QT) is contraindicated post-cardioversion for TdP.
• D) IV lidocaine (Class Ib) has limited efficacy in TdP and is not first-line.
• E) IV metoprolol is used for congenital long QT syndrome (LQTS1) where beta-blockers are protective; however, in acquired QT prolongation, magnesium is the immediate priority.

• A) Metformin
• B) Amoxicillin
• C) Sotalol
• D) Metoprolol
• E) Aspirin

• A) Metformin has no cardiac ion channel effects and does not prolong QTc.
• B) Amoxicillin does not cause QT prolongation.
• D) Metoprolol does not prolong the QT interval; beta-blockers are actually protective in long QT syndrome (particularly LQT1).
• E) Aspirin does not affect cardiac repolarisation or QTc.

• A) IV amiodarone → IV potassium replacement
• B) IV magnesium → IV potassium replacement → remove offending drug → temporary pacing if recurrent
• C) Synchronised cardioversion → oral sotalol maintenance
• D) Lignocaine → oral amiodarone → permanent pacemaker
• E) Oral verapamil + potassium supplementation only

• A) Amiodarone further prolongs QT and is contraindicated in TdP; should never be given.
• C) Sotalol post-cardioversion would worsen TdP by further prolonging the QTc.
• D) Oral amiodarone is also contraindicated; lidocaine is second-line after magnesium, not first.
• E) Oral verapamil has some benefit in LQT3/specific subtypes but is not the standard management of acquired TdP.

• A) Prophylactic oral amiodarone
• B) No specific intervention; reassure
• C) Implantable cardioverter-defibrillator (ICD) if EF remains ≤35% after ≥3 months of optimal medical therapy
• D) Immediate EP study-guided ablation
• E) Oral mexiletine for VT suppression

• A) Prophylactic amiodarone reduces VT burden but does not reduce overall mortality; it carries significant long-term toxicity and is not a substitute for ICD.
• B) NSVT in the context of EF 22% is not benign and warrants appropriate action per guidelines.
• D) EP-guided ablation is used for recurrent symptomatic VT "VT storm" or ICD discharges, not primary prevention in NSVT.
• E) Oral mexiletine (Class Ib) can suppress VT but does not improve survival; SCD-HeFT showed that antiarrhythmics do not substitute for ICD in primary prevention.

• A) Ischaemic VT from inferior wall scar
• B) Idiopathic left ventricular outflow tract (LVOT) VT
• C) Idiopathic fascicular VT (Belhassen VT)
• D) Catecholaminergic polymorphic VT (CPVT)
• E) Bundle branch re-entry VT

• A) Ischaemic VT from inferior scar would have inferior axis (positive in inferior leads) and is associated with prior MI scar.
• B) LVOT VT characteristically has LBBB morphology with inferior axis (positive in II, III, aVF); it is exercise-induced.
• D) CPVT is characteristically exercise-induced, bidirectional, or polymorphic VT in young patients with structurally normal hearts and ryanodine receptor mutations.
• E) Bundle branch re-entry VT requires cardiomyopathy and produces LBBB morphology with ablation target at the right bundle; not applicable in a structurally normal heart.

• A) Amiodarone-induced hyperthyroidism
• B) Amiodarone-induced pulmonary toxicity
• C) Fluid overload from amiodarone-induced hypothyroidism
• D) Acute interstitial nephritis
• E) Amiodarone-induced hepatotoxicity causing hypoalbuminaemia

• A) Amiodarone-induced thyrotoxicosis would cause suppressed TSH (not elevated); the raised TSH here indicates hypothyroidism, which alone would not explain bilateral pulmonary infiltrates.
• C) Hypothyroidism can cause fluid retention but would not produce the bilateral reticular infiltrates characteristic of amiodarone pneumonitis.
• D) Acute interstitial nephritis is not a recognised amiodarone toxicity; amiodarone can elevate creatinine by decreasing tubular secretion without true renal toxicity.
• E) Hepatotoxicity from amiodarone causes elevated transaminases; hypoalbuminaemia would suggest chronic liver failure, not typical of amiodarone hepatotoxicity alone.

• A) 24-hour Holter monitoring
• B) Electrophysiology (EP) study
• C) Coronary angiography to exclude ischaemic aetiology
• D) Brain natriuretic peptide (BNP) level
• E) Signal-averaged ECG

• A) Holter monitoring is useful for documenting arrhythmias; it is secondary to identifying the structural cause.
• B) EP study guides VT ablation and risk stratification but should follow structural/coronary evaluation.
• D) BNP reflects haemodynamic stress and heart failure status; it does not guide the aetiology or definitive management of VT.
• E) Signal-averaged ECG detects late potentials (scar-related VT substrate) but is not first-line; coronary evaluation comes first.

• A) LBBB pattern + right axis deviation + fever-induced VT
• B) Coved (type 1) ST elevation ≥2 mm in V1–V2 + documented VF or unexplained syncope + absence of other causes
• C) Short QT interval + tall peaked T waves + polymorphic VT
• D) Delta waves + pre-excited AF + syncope
• E) Prolonged QTc >480 ms + recurrent torsades + deafness

• A) LBBB + right axis deviation + fever-induced VT is not classic Brugada; Brugada features RBBB-like pattern in V1 (coved, not LBBB).
• C) Short QT + tall T waves + polymorphic VT describes Short QT syndrome, not Brugada.
• D) Delta waves + pre-excited AF describe WPW syndrome, not Brugada.
• E) Prolonged QTc + TdP + congenital deafness (Jervell-Lange-Nielsen syndrome) describes congenital LQTS1 (autosomal recessive), not Brugada.

• A) Urgent carotid sinus massage
• B) Increase amiodarone dose to 1200 mg/day
• C) Correction of electrolytes + consider IV beta-blocker (metoprolol/esmolol) for sympathetic suppression
• D) Immediate ICD implantation
• E) Oral verapamil 240 mg

• A) Carotid sinus massage has no role in VT storm management.
• B) Escalating amiodarone beyond therapeutic levels increases toxicity without proven superior VT storm suppression.
• D) ICD implantation is a long-term strategy; it does not address acute VT storm episodes in progress.
• E) Oral verapamil has insufficient bioavailability and onset for acute VT storm; IV verapamil is specific to fascicular VT.

• A) Long QT syndrome type 1
• B) Brugada syndrome
• C) Arrhythmogenic right ventricular cardiomyopathy (ARVC)
• D) Catecholaminergic polymorphic ventricular tachycardia (CPVT)
• E) Hypertrophic obstructive cardiomyopathy

• A) LQT1 causes exercise-triggered syncope but the VT morphology is polymorphic (TdP) with prolonged QTc; bidirectional VT is not characteristic.
• B) Brugada syndrome typically causes arrhythmias at rest or with fever, not during exercise; it does not produce bidirectional VT.
• C) ARVC presents with VT from the right ventricle (LBBB morphology), epsilon waves, and right ventricular structural changes; not bidirectional.
• E) HOCM can cause exercise-related syncope and VT, but bidirectional VT with normal heart structure on echo is not typical.

• A) Prescribing aspirin to a patient with dengue fever
• B) Prescribing metformin to a patient with eGFR 42 mL/min
• C) Prescribing IV erythromycin to a patient already on methadone and with baseline QTc of 490 ms
• D) Prescribing amoxicillin to a penicillin-allergic patient
• E) Prescribing atenolol to a patient with asthma

• A) Aspirin in dengue increases bleeding risk (thrombocytopaenia) but does not cause TdP.
• B) Metformin at eGFR 42 is a cautionary zone for lactic acidosis risk but does not cause TdP.
• D) Penicillin allergy raises anaphylaxis risk, not TdP.
• E) Beta-blockers in asthma risk bronchospasm, not TdP.

━━━ SECTION D: AV BLOCKS & BRADYARRHYTHMIAS (Questions 38–44) ━━━

• A) Permanent pacemaker implantation
• B) IV atropine 0.5 mg
• C) Observation; first-degree AV block alone rarely requires treatment
• D) Temporary transvenous pacing
• E) Oral metoprolol 25 mg twice daily

• A) Pacemaker implantation is not indicated for first-degree AV block alone; it is only considered if symptomatic (very long PR >300 ms causing "pacemaker syndrome" with AV dyssynchrony).
• B) IV atropine is for acute symptomatic bradycardia; this patient has normal rate with only PR prolongation.
• D) Temporary pacing is for haemodynamically compromising bradycardia; not indicated here.
• E) Metoprolol would further slow AV conduction and worsen first-degree block; it is contraindicated in this context.

• A) Mobitz type II AV block; urgent permanent pacemaker
• B) Mobitz type I (Wenckebach) AV block; often benign, pacemaker only if symptomatic
• C) Third-degree AV block; urgent temporary pacing
• D) 2:1 AV block; empirical digoxin
• E) First-degree AV block with aberrant conduction

• A) Mobitz II shows constant PR interval before a sudden dropped beat (infra-nodal block); it has a much higher risk of progression to complete heart block and warrants pacemaker regardless of symptoms.
• C) Third-degree AV block shows complete AV dissociation (P waves and QRS at independent rates) — not present here.
• D) 2:1 AV block has alternating conducted and non-conducted P waves; digoxin would further worsen conduction.
• E) First-degree AV block involves PR >200 ms on every beat without dropped beats.

• A) Wenckebach (Mobitz I) block; reassure and observe
• B) Mobitz type II AV block; urgent permanent pacemaker indicated
• C) Third-degree AV block; IV atropine then temporary pacing
• D) Sick sinus syndrome; oral propranolol
• E) Vagal syncope; tilt table testing

• A) Wenckebach (Mobitz I) shows progressive PR prolongation; the constant PR before the dropped beat here excludes Wenckebach.
• C) Third-degree AV block shows consistent complete AV dissociation with escape rhythm; atropine is ineffective in infranodal block and is a classic HKMLE trap (atropine in Mobitz II — see Q42).
• D) Sick sinus syndrome affects sinus node automaticity, not AV conduction; wide QRS points to infranodal pathology.
• E) Vasovagal syncope in a 68-year-old with LBBB and documented AV block would be a missed dangerous diagnosis.

• A) Immediate transvenous temporary pacing
• B) IV atropine 1 mg
• C) IV isoprenaline (isoproterenol) infusion
• D) Watchful waiting; inferior STEMI-related complete heart block is often transient and resolves with reperfusion
• E) Urgent permanent pacemaker

• A) Temporary pacing is indicated if the patient is symptomatic, haemodynamically unstable, or escape rate is very slow (<40 bpm); this patient is stable with HR 45 bpm.
• B) IV atropine can be tried first if symptomatic in inferior MI-associated CHB (vagal mechanism); it may work in nodal block.
• C) Isoprenaline is rarely used and reserved for atropine-unresponsive cases; not first-line.
• E) Permanent pacemaker is generally not required unless high-grade AV block persists >10–14 days post-inferior MI.

• A) No error; atropine is first-line for all bradycardias
• B) Error: atropine is ineffective (and potentially harmful) in infranodal complete heart block; transcutaneous or transvenous pacing should have been initiated immediately
• C) Error: atropine dose too low; 3 mg should have been given
• D) No error; atropine is indicated in haemodynamically unstable CHB
• E) Error: IV adrenaline (epinephrine) 1 mg should have been given first

• A) Atropine is indicated for sinus bradycardia, AV nodal (proximal) block; not infranodal block.
• C) Higher doses of atropine are equally ineffective in infranodal block; the mechanism is not vagal.
• D) Even in haemodynamic instability, atropine is ineffective in infranodal block; it wastes critical time.
• E) IV adrenaline 1 mg is for cardiac arrest (VF/pulseless VT); though it can transiently increase escape rate, it is not appropriate management here — pacing is.

• A) Mobitz II AV block; permanent pacemaker with atropine bridge
• B) Sick sinus syndrome (tachy-brady syndrome); permanent pacemaker (DDDR or AAIR pacing preferred) + consideration of rate control agents if paced
• C) Paroxysmal AF with RVR; oral digoxin + cardioversion
• D) Vasovagal syncope; reassurance and increased fluid/salt intake
• E) AVNRT with post-conversion pause; IV adenosine

• A) Mobitz II involves sudden AV conduction block; this ECG shows sinus node dysfunction with tachyarrhythmia, not AV block.
• C) While paroxysmal AF can be part of the picture, treatment with digoxin alone without pacemaker backup would not address the bradycardia component safely.
• D) Vasovagal syncope does not produce intrinsic sinus pauses or tachyarrhythmias on Holter; the pattern here is structural sinus node disease.
• E) Post-adenosine pauses occur after SVT termination, but this pattern persists recurrently, indicating intrinsic sick sinus syndrome.

• A) Lyme carditis causing AV block
• B) Digitalis toxicity
• C) Physiological vagotonia in a trained athlete; no action required
• D) Hypertrophic cardiomyopathy
• E) Acute myocarditis

• A) Lyme carditis can cause AV block that worsens with exercise; improvement with exercise argues against Lyme disease.
• B) Digitalis toxicity typically produces multiple AV block patterns with bradycardia; no drug use is mentioned.
• D) HOCM may cause LVH and arrhythmias; it is not associated with AV block that resolves with exercise.
• E) Myocarditis would have associated symptoms (fever, chest pain, raised troponin) and does not explain exercise-related improvement.

━━━ SECTION E: BUNDLE BRANCH BLOCKS & ANTIARRHYTHMICS (Questions 45–50) ━━━

• A) Left bundle branch block (LBBB)
• B) Right bundle branch block (RBBB)
• C) Left anterior fascicular block
• D) Bifascicular block
• E) Wolff-Parkinson-White syndrome

• A) LBBB produces: broad QRS; no septal Q waves; broad monophasic R in I, aVL, V5, V6; broad rS or QS in V1 (no R' in V1); it is essentially the opposite pattern to RBBB.
• C) LAFB produces left axis deviation (−45° to −90°) with narrow QRS and rS pattern in inferior leads; it does not widen QRS significantly.
• D) Bifascicular block = RBBB + LAFB or LPFB; characterised by RBBB pattern plus axis deviation but requires both criteria.
• E) WPW shows short PR + delta wave + widened QRS; the morphology and context differ from a pure conduction block.

• A) New LBBB always confirms acute STEMI equivalent; immediate cath lab activation
• B) New LBBB in the appropriate clinical context (chest pain, haemodynamic instability) should be treated as STEMI equivalent; use Sgarbossa criteria to confirm ischaemia
• C) New LBBB excludes STEMI as repolarisation assessment is impossible
• D) New LBBB should be managed with IV amiodarone first
• E) New LBBB is always benign and requires only outpatient follow-up

• A) Not all new LBBB is STEMI; the 2017 ESC STEMI guidelines revised this position from "always activate" to "context-dependent" — new LBBB alone without symptoms/haemodynamic instability may not warrant immediate cath lab.
• C) While LBBB makes standard ST-elevation criteria unreliable, ischaemia can be detected using Sgarbossa criteria.
• D) IV amiodarone addresses arrhythmia, not ischaemia; it has no role in new LBBB with chest pain.
• E) New LBBB in the context of chest pain warrants urgent evaluation; it is never to be dismissed outright as benign.

• A) Lidocaine (lignocaine)
• B) Flecainide
• C) Procainamide
• D) Verapamil
• E) Amiodarone

• A) Lidocaine is Class Ib — fast sodium channel blocker with minimal effects on AP duration; it shortens rather than prolongs the AP; used primarily for VT, not WPW or AF.
• B) Flecainide is Class Ic — potent fast sodium channel blocker with minimal AP prolongation; it is contraindicated in structural heart disease and is not preferred in pre-excited AF (can enhance accessory pathway conduction).
• D) Verapamil is Class IV — L-type calcium channel blocker; it has no sodium channel activity.
• E) Amiodarone is Class III (primarily) but also Classes I, II, IV; it prolongs AP most prominently via potassium channel blockade; it is used for VT/AF but is not the specific answer here given its broader mechanism.

• A) Class Ia (e.g., quinidine)
• B) Class Ib (e.g., lidocaine)
• C) Class Ic (e.g., flecainide)
• D) Class II (e.g., metoprolol)
• E) Class III (e.g., sotalol, amiodarone)

• A) Class Ia agents (quinidine, procainamide) block both sodium channels (Class I) AND potassium channels (Class III-like) — they prolong AP but their primary action is sodium channel blockade.
• B) Class Ib agents (lidocaine, mexiletine) block sodium channels and actually shorten AP duration; minimal QT change.
• C) Class Ic agents (flecainide, propafenone) are potent sodium channel blockers with minimal effect on AP duration; QRS widens but QT changes are minimal.
• D) Class II agents (beta-blockers) block beta-adrenergic receptors, reducing sinus rate and AV conduction; they do not directly block IKr.

• A) Torsades de pointes from QT prolongation by flecainide
• B) Atrial flutter with 1:1 AV conduction (flecainide-induced flutter)
• C) Wolff-Parkinson-White syndrome unmasked by flecainide
• D) Digoxin toxicity
• E) Hyperthyroidism-induced AF

• A) Flecainide (Class Ic) widens QRS but minimally prolongs QTc; it does not commonly cause TdP — that is the risk of Class Ia and III agents.
• C) WPW is not unmasked by flecainide; pre-existing delta waves would have been visible on baseline ECG.
• D) Digoxin toxicity produces bradycardia and AV block, not regular wide-complex tachycardia.
• E) Hyperthyroidism accelerates AF but does not produce regular wide-complex tachycardia.

• A) Pulmonary toxicity is dose-independent and can occur at low doses after short exposure
• B) Annual monitoring of TFTs, LFTs, CXR, and ophthalmology review is recommended; corneal microdeposits are universal and not an indication to stop treatment
• C) Amiodarone should be stopped immediately for any elevation of TSH
• D) Annual DLCO is the gold standard for early pulmonary toxicity detection and mandates drug discontinuation when reduced by 15%
• E) Corneal microdeposits causing "halos" are rare and indicate irreversible corneal damage

• A) Pulmonary toxicity is typically dose-dependent and cumulative (>400 mg/day, >2 years); however, rare cases occur at lower doses; the statement "dose-independent" is inaccurate.
• C) Isolated TSH elevation (hypothyroidism) should be treated with levothyroxine; amiodarone need not be stopped unless thyrotoxicosis is severe (Type II AIT) or the indication for amiodarone is weak.
• D) DLCO reduction is a sensitive marker of pulmonary toxicity but the threshold for stopping is clinical judgement (symptoms + imaging); 15% reduction alone is not a mandatory stopping criterion.
• E) Corneal microdeposits are virtually universal (not rare) and reversible (not irreversible) on drug discontinuation; they rarely affect visual acuity significantly.

━━━ SUBTOPIC SUMMARY TABLE ━━━

⚠️ High-Yield HKMLE Trap Answers — Summary

📚 References

• Harrison's Principles of Internal Medicine, 22nd Edition (2025, McGraw-Hill)
• Washington Manual of Medical Therapeutics, 36th Edition
• Tintinalli's Emergency Medicine, 9th Edition
• Rosen's Emergency Medicine, 9th Edition
• 2024 ESC Guidelines for the Management of Atrial Fibrillation (Van Gelder IC et al., Eur Heart J. 2024 Sep 29; PMID: 39210723)
• Davidson's Principles & Practice of Medicine, 24th Edition
• Vaughan Williams EM. Classification of antiarrhythmic drugs (1970; updated Sicilian Gambit 1991)